PCB transformer and design method, dc / dc converter, power module

Abstract

The application provides a PCB transformer, a design method, a DC / DC converter and a power module, wherein the design method comprises the following steps: determining the single-turn winding width based on the window size of a magnetic core; determining the branch winding width based on the transformer center frequency and the winding material parameters, and determining the single-turn branch number based on the single-turn winding width and the branch winding width; determining the number of single-turn branch windings of the primary side and the secondary side based on the transformer type and the single-turn branch number to determine the transverse stagger mode, and determining the longitudinal stagger mode based on the turn difference of the primary side and the secondary side; designing the branch windings of the primary side and the secondary side in parallel based on the number of single-turn branch windings of the primary side and the secondary side, and stagger designing each single-turn winding of the primary side and the secondary side based on the transverse and longitudinal stagger modes to obtain a PCB winding plate. The application solves the problems of the existing single-turn copper PCB transformer, such as being greatly affected by the skin effect and the proximity effect, and having large parasitic capacitance and leakage inductance of the primary side and the secondary side.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and in particular to a PCB transformer and its design method, a DC / DC converter, and a power module. Background Technology

[0002] With the miniaturization of electronic devices, traditional wound transformers can no longer meet the needs of modern electronic equipment. Therefore, miniaturized planar transformers have begun to be widely used in small and medium power isolated power modules, such as in the power supply fields of aerospace, robotics, and electric vehicles. PCB transformers with flattened windings have advantages such as high window utilization, high customization, good consistency and reliability, large heat dissipation area, ability to adapt to large current densities with low temperature rise, simple manufacturing process, and low production cost, and are widely used in planar transformer applications.

[0003] The operating characteristics of PCB transformers at different frequencies are important factors to consider during design and selection. For PCB transformers operating at low frequencies, the design is usually relatively simple because the influence of parasitic parameters (such as leakage inductance, resistance, and capacitance) is relatively small and can be ignored. However, when PCB transformers are used under high-frequency conditions, the influence of these parasitic parameters becomes significant and may seriously affect circuit stability, component withstand voltage, and lifespan.

[0004] Existing PCB transformers typically use single-turn copper strip windings. Under high-frequency conditions, the skin effect and proximity effect of the windings reduce the effective conduction area, increase AC impedance, and increase eddy current losses, thereby reducing transformer efficiency and causing significant heat generation variations. Furthermore, the planar winding structure of the primary and secondary sides generates large parasitic capacitances, which can easily induce high-frequency interference signals such as voltage spikes and common-mode noise, affecting circuit stability. Therefore, designing PCB transformers to ensure their operating characteristics under high-frequency conditions is crucial for circuit design and optimization.

[0005] It should be noted that the above description of the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of the present invention and facilitating understanding by those skilled in the art. It should not be assumed that the above technical solutions are known to those skilled in the art simply because they have been described in the background section of this invention. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a PCB transformer and its design method, a DC / DC converter, and a power module to solve the problems of existing single-turn copper PCB transformers being greatly affected by the skin effect and proximity effect, and having large parasitic capacitance and leakage inductance on the primary and secondary sides.

[0007] To achieve the above and other related objectives, the present invention provides a design method for a PCB transformer, the design method comprising:

[0008] The width of a single-turn winding is determined based on the window size of the magnetic core;

[0009] The branch winding width is determined based on the center frequency of the PCB transformer and the electromagnetic parameters of the selected winding material, and the number of single-turn branches is determined based on the single-turn winding width and the branch winding width.

[0010] Based on the type of the PCB transformer and the number of single-turn branches, the number of primary single-turn branch windings and the number of secondary single-turn branch windings are determined, and the transverse interleaving pattern of each primary single-turn branch winding in the primary single-turn winding and each secondary single-turn branch winding in the secondary single-turn winding is determined accordingly. Based on the primary and secondary turn difference of the PCB transformer, the longitudinal interleaving pattern of each primary single-turn winding in the primary winding and each secondary single-turn winding in the secondary winding is determined.

[0011] Based on the number of primary side single-turn branch windings and the number of secondary side single-turn branch windings, the branch windings of the primary side single-turn windings and the secondary side single-turn windings are designed in parallel. Based on the longitudinal and transverse interleaving methods, the primary side single-turn windings and the secondary side single-turn windings are designed in an interleaving manner, and the PCB winding board is obtained in this way.

[0012] Optionally, the method for determining the window size includes: determining the window size based on the power rating of the PCB transformer.

[0013] Optionally, the design method further includes: determining the material of the magnetic core based on the switching frequency of the PCB transformer, and thereby determining the magnetic core by means of the window size and material of the magnetic core.

[0014] Optionally, the width of the single-turn winding satisfies the formula W = W W -2W R Where W is the width of a single-turn winding, W W W is the window width. R The width is for safety regulations; when the PCB transformer is a step-up transformer, the width of the single-turn winding is the width of the primary single-turn winding; when the PCB transformer is a step-down transformer, the width of the single-turn winding is the width of the secondary single-turn winding.

[0015] Optionally, the width of the branch winding satisfies the formula w i =2kδ, ω = 2πf; where w idenoted as the branch winding width, k as the scaling factor, δ as the skin depth, ρ as the resistivity of the selected winding material, σ as the conductivity of the selected winding material, μ as the permeability of the selected winding material, ω as the angular frequency, and f as the center frequency of the PCB transformer.

[0016] Optionally, the number of single-turn branches satisfies the formula When the PCB transformer is a step-up transformer, the number of primary single-turn branch windings satisfies the formula n. p =n, the number of the secondary single-turn branch windings satisfies the formula n s =n p -1; When the PCB transformer is a step-down transformer, the number of single-turn branch windings on the secondary side satisfies formula n s =n, the number of primary side single-turn branch windings satisfies the formula n p =n s -1; where n is the number of single-turn branches, W is the width of a single-turn winding, and w i n is the width of the branch winding. p n is the number of single-turn branch windings on the primary side. s This represents the number of single-turn branch windings on the secondary side.

[0017] Optionally, when the number of primary-side single-turn branch windings is greater than the number of secondary-side single-turn branch windings, the lateral interleaving method includes: in the horizontal projection of the primary-side single-turn windings and the secondary-side single-turn windings, each secondary-side single-turn branch winding is located in the gap between each primary-side single-turn branch winding; when the number of primary-side single-turn branch windings is less than the number of secondary-side single-turn branch windings, the lateral interleaving method includes: in the horizontal projection of the primary-side single-turn windings and the secondary-side single-turn windings, each primary-side single-turn branch winding is located in the gap between each secondary-side single-turn branch winding.

[0018] Optionally, when the primary-secondary turn difference is equal to -1, the longitudinal interleaving method includes: using a fully interleaved structure to longitudinally interleave each of the primary single-turn windings and each of the secondary single-turn windings, wherein the secondary single-turn windings are used as the top and bottom layers of the fully interleaved structure; when the primary-secondary turn difference is less than -1, the longitudinal interleaving method includes: using a segmented interleaved structure to longitudinally interleave each of the primary single-turn windings and each of the secondary single-turn windings, wherein each segment adopts a fully interleaved structure;

[0019] When the primary-secondary turn difference is equal to 1, the longitudinal interleaving method includes: using a fully interleaved structure to longitudinally interleave each of the primary single-turn windings and each of the secondary single-turn windings, wherein the primary single-turn windings are used as the top and bottom layers of the fully interleaved structure; when the primary-secondary turn difference is greater than 1, the longitudinal interleaving method includes: using a segmented interleaved structure to longitudinally interleave each of the primary single-turn windings and each of the secondary single-turn windings, wherein each segment adopts a fully interleaved structure.

[0020] Optionally, the method of using a segmented interleaved structure for longitudinal interleaved layout includes: determining the number of segments; dividing each primary-side single-turn winding and each secondary-side single-turn winding into multiple segments based on the number of segments; and using a fully interleaved structure to longitudinally interleave each primary-side single-turn winding and each secondary-side single-turn winding in each segment; wherein, the number of segments satisfies the formula m = max(N P N S )-min(N P N S ), m is the number of segments, max(N) P N S ) is N P and N S The maximum value in, min(N) P N S ) is N P and N S The minimum value in N P N represents the number of single-turn windings on the primary side. S This represents the number of single-turn windings on the secondary side.

[0021] Optionally, in the fully interleaved structure, when the primary-secondary turn difference is less than 0, in the vertical projection of the primary winding and the secondary winding, each primary single-turn winding is located in the gap between each secondary single-turn winding; when the primary-secondary turn difference is greater than 0, in the vertical projection of the primary winding and the secondary winding, each secondary single-turn winding is located in the gap between each primary single-turn winding.

[0022] The present invention also provides a PCB transformer, the PCB transformer comprising:

[0023] Magnetic core and PCB winding board;

[0024] The magnetic core includes a first magnetic core body and a second magnetic core body, which are arranged opposite each other through pillars to form a window. The pillars include edge pillars and a center pillar.

[0025] The PCB winding board is fixed in the window by the central post;

[0026] The magnetic core is obtained using the design method described above, and the PCB winding board is obtained using the design method described above.

[0027] The present invention also provides a DC / DC converter, the DC / DC converter comprising: a PCB transformer as described above.

[0028] The present invention also provides a power supply module, the power supply module comprising: the DC / DC converter as described above.

[0029] As described above, the PCB transformer and design method, DC / DC converter, and power module of the present invention design both the primary winding and the secondary winding as multi-turn structures (the primary winding includes multiple primary single-turn windings, and the secondary winding includes multiple secondary single-turn windings). At the same time, both the primary single-turn winding and the secondary single-turn winding are designed as multi-branch parallel structures, and each primary single-turn winding and each secondary single-turn winding is staggered in the longitudinal direction, and each branch winding in adjacent primary single-turn windings and secondary single-turn windings is staggered in the transverse direction.

[0030] In the above structural optimizations: the parallel design can improve the overall current density distribution of single-turn windings on the primary and secondary sides, reduce the influence of skin effect and proximity effect, and reduce eddy current loss and high-frequency AC loss; the transverse staggered design can reduce or even eliminate parasitic capacitance between single-turn windings on the primary and secondary sides, block the EMI common-mode current transmission path, and improve the EMI immunity of the PCB transformer; the longitudinal staggered design can enhance the magnetic coupling between the primary and secondary windings, reduce the leakage inductance of the PCB transformer, and improve the electromagnetic conversion efficiency. This invention can effectively improve the high-frequency performance of PCB transformers, ensure their stability under high-frequency conditions, and has high practical value. Attached Figure Description

[0031] Figure 1 The flowchart shown is a PCB transformer design method of the present invention.

[0032] Figure 2 The diagram shown is a structural schematic of a PCB transformer according to the present invention.

[0033] Figure 3 The diagram shown is a structural schematic of a single-turn primary winding in the PCB transformer of this invention.

[0034] Figure 4 The diagram shown is a structural schematic of a single-turn secondary winding in the PCB transformer of this invention.

[0035] Figure 5 The diagram shows a schematic of the horizontally staggered arrangement of the branch windings in the primary and secondary single-turn windings of the PCB transformer of the present invention.

[0036] Figure 6 Displayed as Figure 5 A schematic diagram of the dashed box portion projected horizontally.

[0037] Figure 7 The diagram shows a longitudinally staggered arrangement of the primary and secondary single-turn windings in the PCB transformer of this invention.

[0038] Figure 8 The diagram shows the relationship between the skin depth of different winding materials and frequency.

[0039] Figure 9 The diagram shows a comparison of the parasitic capacitance of the PCB transformer of this invention and a traditional PCB transformer.

[0040] Figure 10 The diagram shows a comparison of the AC impedance of the PCB transformer of this invention and a traditional PCB transformer.

[0041] Component designation explanation

[0042] 100 PCB Transformer

[0043] 110 magnetic core

[0044] 111 First magnetic core

[0045] 112 Second magnetic core

[0046] 113 Columns

[0047] 114 Window

[0048] 120 PCB winding board

[0049] 121 Primary winding

[0050] 121a Primary single-turn winding

[0051] 121a' Primary single-turn branch winding

[0052] 122 secondary winding

[0053] 122a Secondary single-turn winding

[0054] 122a' Secondary single-turn branch winding Detailed Implementation

[0055] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0056] Please see Figures 1 to 10 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the shape, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0057] like Figure 1 As shown, this embodiment provides a design method for a PCB transformer, including steps S1 to S4, and further including step S0.

[0058] Step S0 involves determining the window size of the magnetic core based on the power rating of the PCB transformer; further, it also includes determining the material of the magnetic core based on the switching frequency of the PCB transformer, thereby realizing the determination of the magnetic core through the window size and material.

[0059] The power rating and switching frequency are design specifications for PCB transformers, determined by the application scenario. The power rating determines the size of the core window; generally, the higher the power rating, the larger the core window. The switching frequency determines the core material; typically, high switching frequencies (e.g., switching frequencies greater than 300kHz) correspond to high-frequency core materials, and low switching frequencies correspond to low-frequency core materials.

[0060] In fact, determining the core window size based on power rating and the core material based on switching frequency are well-known techniques to those skilled in the art, and will not be elaborated here. Furthermore, the window width is of particular interest in the window size, as it determines the width of a single-turn winding. The window depth is determined by the thickness of the PCB winding board, which in turn is determined by the number of primary and secondary single-turn windings. The window length is determined by the window shape, which can be rectangular, annular, etc., and can be designed according to actual conditions; this embodiment does not impose any limitations on this.

[0061] It should be noted that the method for determining the core material can be performed before or after the method for determining the core window size. This embodiment does not restrict the order of execution of the two methods. Of course, the method for determining the core material may also be omitted from this step, such as in other steps, or even before or after other steps, which has no substantial impact on this embodiment.

[0062] Step S1: Determine the width of a single-turn winding based on the window size of the magnetic core.

[0063] In one implementation, the width of a single-turn winding satisfies the formula W = W W -2W RWhere W is the width of a single-turn winding, W W W is the window width. R This refers to the safety specification width. It is important to note that when designing the winding at the position corresponding to the core window on the PCB winding board, a certain safety distance must be maintained between the winding and the core to avoid forming a circuit. For safety reasons, a safety specification width is reserved near the edge of the core window. Therefore, the width of a single-turn winding can be obtained by subtracting twice the safety specification width from the window width.

[0064] In this embodiment, the width of a single-turn winding is actually the maximum width of a single-turn winding. Whether it is the width of the primary-side single-turn winding or the width of the secondary-side single-turn winding depends on the type of PCB transformer. For example, when the PCB transformer is a step-up transformer, it is the width of the primary-side single-turn winding, satisfying the formula W. P =W; When the PCB transformer is a step-down transformer, it is the width of a single turn of the secondary winding, which satisfies the formula W. S =W;W P W is the width of the primary single-turn winding. S This refers to the width of a single-turn secondary winding. This embodiment considers the current characteristics of the primary and secondary windings in a step-up or step-down transformer when designing the width of the single-turn winding. It allows for winding design based on the maximum current density, avoiding transformer overheating and failure due to excessive current in the primary or secondary windings.

[0065] Step S2: Determine the branch winding width based on the center frequency of the PCB transformer and the electromagnetic parameters of the selected winding material, and determine the number of single-turn branches based on the single-turn winding width and the branch winding width.

[0066] The center frequency is a design specification for PCB transformers, usually determined by the application scenario. The winding material is also determined by the application scenario. In general applications, copper is usually chosen as the winding material. In some special applications, gold, silver, aluminum, etc. are chosen as the winding material. As the winding material is selected, its electromagnetic parameters are also determined. Among them, electromagnetic parameters include resistivity and permeability. Of course, resistivity can also be replaced by conductivity, and the two are reciprocals of each other.

[0067] In one implementation, the skin depth is first determined based on the center frequency of the PCB transformer and the electromagnetic parameters of the selected winding material, then the scaling factor is selected, and finally the branch winding width is determined based on the skin depth and the scaling factor.

[0068] Skin depth refers to the thickness from the conductor surface to 0.368 (i.e., 1 / e) of the surface current density; such as Figure 8As shown, different conductor materials have different skin depths at the same frequency. Therefore, it is necessary to calculate the skin depth based on the center frequency of the PCB transformer and the selected winding material.

[0069] The scaling factor is determined by the application scenario. If the application scenario has high requirements for parasitic capacitance, the scaling factor should be smaller. If the application scenario has low requirements for parasitic capacitance, the scaling factor can be larger. In applications, the scaling factor is generally taken as 1, so as to obtain better current density distribution and high-frequency AC impedance.

[0070] Among them, the branch winding width satisfies the formula w i =2kδ, ω=2πf;w i Let w be the branch winding width, k be the scaling factor, δ be the skin depth, ρ be the resistivity of the selected winding material, σ be the conductivity of the selected winding material, μ be the permeability of the selected winding material, ω be the angular frequency, and f be the center frequency of the PCB transformer. It is important to note that when designing the windings, whether it is a primary single-turn winding or a secondary single-turn winding, the width of the branch winding is always w. i And by default, its thickness and width are equal, both being w. i .

[0071] In one implementation, the number of single-turn branches satisfies the formula... Where n is the number of single-turn branches, W is the width of a single-turn winding, and w i The width of the branch winding is 2w. In this embodiment, the width of a single-turn winding W is twice the width of the branch winding, 2w. i The ratio is denoted as x, and the number of single-turn branches n takes the smallest integer not less than x; by designing twice the width of the branch winding, it is convenient to design the transverse staggered design of each primary single-turn branch winding in the primary single-turn winding and each secondary single-turn branch winding in the secondary single-turn winding.

[0072] Step S3: Determine the number of primary single-turn branch windings and secondary single-turn branch windings based on the type and number of single-turn branches of the PCB transformer. Then, determine the transverse interleaving pattern of each primary single-turn branch winding in the primary single-turn winding and each secondary single-turn branch winding in the secondary single-turn winding, and determine the longitudinal interleaving pattern of each primary single-turn winding in the primary winding and each secondary single-turn winding in the secondary winding based on the primary-secondary turn difference of the PCB transformer.

[0073] When the PCB transformer is a step-up transformer, the number of single-turn turns in the primary winding is less than the number of single-turn turns in the secondary winding, and the primary-to-secondary turn difference is less than 0. In this case:

[0074] The number of primary single-turn branch windings satisfies the formula n p=n, the number of single-turn branch windings on the secondary side satisfies the formula n s =n p -1; where n is the number of single-turn branches, n p n is the number of single-turn branch windings on the primary side. s This refers to the number of single-turn branch windings on the secondary side. In this embodiment, as shown... Figure 3 and Figure 4 As shown, the primary single-turn branch windings in the primary single-turn winding are connected in parallel, and the secondary single-turn branch windings in the secondary single-turn winding are connected in parallel. Through the parallel design, the current density distribution of the primary and secondary single-turn windings is more uniform, which helps to reduce the influence of skin effect and proximity effect, and reduce eddy current loss and high-frequency AC loss. The number of primary single-turn branch windings is greater than the number of secondary single-turn branch windings, and the difference between the two is 1, which facilitates the lateral staggering of the branch windings in the primary and secondary single-turn windings.

[0075] The transverse interleaving method includes: in the horizontal projection of the primary and secondary single-turn windings, each secondary single-turn branch winding is located in the gap between each primary single-turn branch winding. This results in almost no directly opposite area between the branch windings of the secondary and primary single-turn windings, reducing or even eliminating parasitic capacitance between them, blocking the EMI common-mode current transmission path, improving the EMI immunity performance of the PCB transformer, and enhancing the stability and reliability of the PCB transformer. (The last sentence appears to be incomplete and possibly refers to a different method.) p =5 and n s Taking 4 as an example, when the windings are horizontally interleaved, the horizontal projections of the primary and secondary single-turn windings, from the outside to the inside, are as follows: the first primary single-turn branch winding, the first secondary single-turn branch winding, the second primary single-turn branch winding, the second secondary single-turn branch winding, the third primary single-turn branch winding, the third secondary single-turn branch winding, the fourth primary single-turn branch winding, the fourth secondary single-turn branch winding, and the fifth primary single-turn branch winding. Figure 5 and Figure 6 As shown.

[0076] In a step-up transformer, the number of primary single-turn windings is less than the number of secondary single-turn windings, and the turn difference between the primary and secondary windings is less than 0. By longitudinally interleaving the primary and secondary single-turn windings, the magnetic coupling between the primary and secondary windings can be enhanced, the leakage inductance of the PCB transformer can be reduced, and the electromagnetic conversion efficiency can be improved.

[0077] In one embodiment, when the difference between the primary and secondary turns is equal to -1, that is, when the difference between the number of primary single-turn windings and secondary single-turn windings is equal to -1, the longitudinal interleaving method includes: using a fully interleaved structure to longitudinally interleave each primary single-turn winding and each secondary single-turn winding, wherein the secondary single-turn windings are used as the top and bottom layers of the fully interleaved structure.

[0078] In a fully interleaved structure, in the vertical projection of the primary and secondary windings, each primary single-turn winding is located in the gap between each secondary single-turn winding. Taking an example where the number of primary single-turn windings is equal to 3 and the number of secondary single-turn windings is equal to 4, in the fully interleaved structure, in the vertical projection of the primary and secondary windings, from top to bottom, they are: the first secondary single-turn winding, the first primary single-turn winding, the second secondary single-turn winding, the second primary single-turn winding, the third secondary single-turn winding, the third primary single-turn winding, and the fourth secondary single-turn winding.

[0079] In another implementation, when the difference between the number of primary and secondary turns is less than -1, that is, when the difference in the number of primary single-turn windings and secondary single-turn windings is less than -1, the longitudinal interleaving method includes: using a segmented interleaving structure to longitudinally interleave each primary single-turn winding and each secondary single-turn winding, and each segment adopts a full interleaving structure; wherein, the method of using a segmented interleaving structure for longitudinal interleaving includes: determining the number of segments, dividing each primary single-turn winding and each secondary single-turn winding into multiple segments based on the number of segments, and using a full interleaving structure to longitudinally interleave each primary single-turn winding and each secondary single-turn winding in each segment; the number of segments satisfies the formula m = max(N P N S )-min(N P N S ), m is the number of segments, max(N) P N S ) is N P and N S The maximum value in, min(N) P N S ) is N P and N S The minimum value in N P N represents the number of single-turn windings on the primary side. S This represents the number of single-turn windings on the secondary side.

[0080] Taking a primary side single-turn winding with 4 turns and a secondary side single-turn winding with 6 turns as an example, the longitudinal staggered structure includes two segments, each of which includes 2 primary side single-turn windings and 3 secondary side single-turn windings. In the segmented staggered structure, the vertical projections of the primary and secondary side windings are, from top to bottom, the first segment and the second segment. In the first segment, from top to bottom, the first secondary side single-turn winding, the first primary side single-turn winding, the second secondary side single-turn winding, the second primary side single-turn winding, and the third secondary side single-turn winding are arranged in sequence. In the second segment, from top to bottom, the fourth secondary side single-turn winding, the third primary side single-turn winding, the fifth secondary side single-turn winding, the fourth primary side single-turn winding, and the sixth secondary side single-turn winding are arranged in sequence.

[0081] When the PCB transformer is a step-down transformer, the number of single-turn turns in the primary winding is greater than the number of single-turn turns in the secondary winding, and the primary-secondary turn difference is greater than 0. In this case:

[0082] The number of single-turn secondary branch windings satisfies the formula n s =n, the number of primary side single-turn branch windings satisfies the formula n p =n s -1; where n is the number of single-turn branch windings, n p n is the number of single-turn branch windings on the primary side. s This refers to the number of single-turn branch windings on the secondary side. In this embodiment, all primary single-turn branch windings in the primary single-turn winding are connected in parallel, and all secondary single-turn branch windings in the secondary single-turn winding are connected in parallel. Through the parallel design, the current density distribution of the primary and secondary single-turn windings is more uniform, which helps to reduce the influence of the skin effect and proximity effect, and reduce eddy current loss and high-frequency AC loss. Furthermore, the number of secondary single-turn branch windings is designed to be greater than the number of primary single-turn branch windings, with the difference between the two being 1, which facilitates the lateral staggering of the branch windings in the primary and secondary single-turn windings.

[0083] The transverse interleaving method includes: in the horizontal projection of the primary and secondary single-turn windings, each primary single-turn branch winding is located in the gap between the secondary single-turn branch windings. This results in almost no directly opposite area between the branch windings in the primary and secondary single-turn windings, reducing or even eliminating parasitic capacitance between them, blocking the EMI common-mode current transmission path, improving the EMI immunity performance of the PCB transformer, and enhancing the stability and reliability of the PCB transformer. (The last sentence appears to be incomplete and possibly refers to a different method.) p =3 and n s Taking 4 as an example, when they are horizontally interleaved, the horizontal projections of the primary single-turn winding and the secondary single-turn winding, from the outside to the inside, are as follows: the first secondary single-turn branch winding, the first primary single-turn branch winding, the second secondary single-turn branch winding, the second primary single-turn branch winding, the third secondary single-turn branch winding, the third primary single-turn branch winding, and the fourth secondary single-turn branch winding.

[0084] In a step-down transformer, the number of primary single-turn windings is greater than the number of secondary single-turn windings, and the turn difference between the primary and secondary windings is greater than 0. By longitudinally interleaving the primary and secondary single-turn windings, the magnetic coupling between the primary and secondary windings can be enhanced, the leakage inductance of the PCB transformer can be reduced, and the electromagnetic conversion efficiency can be improved.

[0085] In one embodiment, when the difference between the primary and secondary turns is equal to 1, that is, when the difference between the number of primary single-turn windings and secondary single-turn windings is equal to 1, the longitudinal interleaving method includes: using a fully interleaved structure to longitudinally interleave each primary single-turn winding and each secondary single-turn winding, wherein the primary single-turn winding is used as the top and bottom layers of the fully interleaved structure.

[0086] In a fully interleaved structure, in the vertical projection of the primary and secondary windings, each secondary single-turn winding is located in the gap between each primary single-turn winding. Taking an example where the number of primary single-turn windings is equal to 4 and the number of secondary single-turn windings is equal to 3, in the fully interleaved structure, in the vertical projection of the primary and secondary windings, from top to bottom, they are: the first primary single-turn winding, the first secondary single-turn winding, the second primary single-turn winding, the second secondary single-turn winding, the third primary single-turn winding, the third secondary single-turn winding, and the fourth primary single-turn winding.

[0087] In another implementation, when the difference between the number of primary and secondary single-turn windings is greater than 1, that is, when the difference between the number of primary single-turn windings and the number of secondary single-turn windings is greater than 1, the longitudinal interleaving method includes: using a segmented interleaving structure to longitudinally interleave each primary single-turn winding and each secondary single-turn winding, and each segment adopts a full interleaving structure; wherein, the method of using a segmented interleaving structure for longitudinal interleaving includes: determining the number of segments, dividing each primary single-turn winding and each secondary single-turn winding into multiple segments based on the number of segments, and using a full interleaving structure to longitudinally interleave each primary single-turn winding and each secondary single-turn winding in each segment; the number of segments satisfies the formula m = max(N P N S )-min(N P N S ), m is the number of segments, max(N) P N S ) is N P and N S The maximum value in, min(N) P N S ) is N P and N S The minimum value in N P N represents the number of single-turn windings on the primary side. S This represents the number of single-turn windings on the secondary side.

[0088] Taking a primary side single-turn winding with 6 turns and a secondary side single-turn winding with 4 turns as an example, the longitudinally interleaved structure includes two segments, each containing 3 primary side single-turn windings and 2 secondary side single-turn windings. In the segmented interleaved structure, the vertical projections of the primary and secondary windings, from top to bottom, are the first and second segments. In the first segment, from top to bottom, the windings are the first primary side single-turn winding, the first secondary side single-turn winding, the second primary side single-turn winding, the second secondary side single-turn winding, and the third primary side single-turn winding. In the second segment, from top to bottom, the windings are the fourth primary side single-turn winding, the third secondary side single-turn winding, the fifth primary side single-turn winding, the fourth secondary side single-turn winding, and the sixth primary side single-turn winding. Figure 7 As shown.

[0089] Step S4: Based on the number of primary-side single-turn branch windings and the number of secondary-side single-turn branch windings, parallel design is performed for the primary-side and secondary-side single-turn windings respectively. Furthermore, based on longitudinal and transverse interleaving methods, interleaving design is performed for each primary-side and secondary-side single-turn winding, thus obtaining the PCB winding board, as shown below. Figure 2 As shown. In practice, dedicated design software is usually used to design the PCB winding board layout, and then the PCB winding board is manufactured based on the layout.

[0090] In this embodiment, the magnetic core is determined based on step S0, and the PCB winding board is determined based on steps S0 to S4. The two are then combined to obtain a PCB transformer. A comparative test of parasitic capacitance and AC impedance is performed on the PCB transformer of this embodiment and a traditional single-turn copper PCB transformer. The test results are as follows: Figure 9 and Figure 10 As shown, the PCB transformer in this embodiment performs better under high-frequency conditions. Of course, the PCB transformer in this embodiment is also suitable for low-frequency conditions, but its advantages cannot be demonstrated.

[0091] Correspondingly, such as Figures 2 to 7 As shown, this embodiment also provides a PCB transformer 100, including a magnetic core 110 and a PCB winding board 120.

[0092] The magnetic core 110 includes a first magnetic core body 111 and a second magnetic core body 112, which are arranged opposite each other via pillars 113 to form a window 114, wherein the pillars 113 include edge pillars and a center pillar. In one embodiment, the magnetic core 110 is obtained by performing step S0 in the above-described design method.

[0093] It should be noted that, as mentioned above, the material and window size of the magnetic core 110 are two relatively important parameters. Other parameters, such as the external dimensions of the magnetic core, the shape of the edge pillars and the center pillar, have no substantial impact on this embodiment, and this embodiment does not impose any restrictions on them.

[0094] The PCB winding board 120 is fixed in the window 114 by a central post. In one embodiment, the PCB winding board 120 is obtained by performing steps S0 to S4 in the above-described design method.

[0095] The PCB winding board 120 includes a board body and through holes. The board body includes multiple layers stacked longitudinally. In any two adjacent layers, a primary single-turn winding 121a and a secondary single-turn winding 122a are designed, such that the primary single-turn windings 121a and secondary single-turn windings 122a are staggered longitudinally. The primary single-turn windings 121a constitute the primary winding 121, and the secondary single-turn windings 122a constitute the secondary winding. The primary single-turn winding 121a includes multiple parallel primary single-turn branch windings 121a', and the secondary single-turn winding 122a includes multiple parallel secondary single-turn branch windings 122a'. The primary single-turn branch windings 121a' and secondary single-turn branch windings 122a' are staggered laterally between adjacent layers. The through-hole penetrates the plate and is fitted to the center post of the magnetic core 110. It should be noted that this fit includes both shape and size.

[0096] Accordingly, this embodiment also provides a DC / DC converter, such as an isolated DC / DC converter, including a PCB transformer; wherein the PCB transformer is implemented using the transformer structure described above. Of course, the DC / DC converter may also include other device structures, such as switching transistors, capacitors, inductors, diodes, etc.

[0097] Accordingly, this embodiment also provides a power supply module, including a DC / DC converter; wherein the DC / DC converter is implemented using the converter structure described above. Of course, the power supply module may also include other structures, such as a power supply unit, a filter, a controller, etc.

[0098] In summary, the PCB transformer and design method, DC / DC converter, and power module of the present invention design both the primary and secondary windings as multi-turn structures (the primary winding includes multiple primary single-turn windings, and the secondary winding includes multiple secondary single-turn windings). Furthermore, both the primary and secondary single-turn windings are designed as multi-branch parallel structures, with each primary and secondary single-turn winding arranged alternately in the longitudinal direction, and adjacent primary and secondary single-turn windings arranged alternately in the transverse direction. In the above structural optimizations: the parallel design can improve the overall current density distribution of single-turn windings on the primary and secondary sides, reduce the influence of skin effect and proximity effect, and reduce eddy current loss and high-frequency AC loss; the transverse staggered design can reduce or even eliminate parasitic capacitance between single-turn windings on the primary and secondary sides, block the EMI common-mode current transmission path, and improve the EMI immunity of the PCB transformer; the longitudinal staggered design can enhance the magnetic coupling between the primary and secondary windings, reduce the leakage inductance of the PCB transformer, and improve the electromagnetic conversion efficiency. This invention can effectively improve the high-frequency performance of PCB transformers and ensure their stability under high-frequency conditions, thus possessing high practical value. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and has high industrial application value.

[0099] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A design method for a PCB transformer, characterized in that, The design method includes: The width of a single-turn winding is determined based on the window size of the magnetic core; The branch winding width is determined based on the center frequency of the PCB transformer and the electromagnetic parameters of the selected winding material, and the number of single-turn branches is determined based on the single-turn winding width and the branch winding width; the branch winding width satisfies the formula... , , w i δ is the width of the branch winding, k is the scaling factor, which is determined by the application scenario's requirements for parasitic capacitance, δ is the skin depth, ρ is the resistivity of the selected winding material, σ is the conductivity of the selected winding material, μ is the permeability of the selected winding material, ω is the angular frequency, and f is the center frequency of the PCB transformer. The number of primary-side single-turn branch windings and the number of secondary-side single-turn branch windings are determined based on the type of the PCB transformer and the number of single-turn branches. This determines the lateral interleaving pattern between the primary-side single-turn branch windings and the secondary-side single-turn branch windings. Furthermore, the longitudinal interleaving pattern between the primary-side single-turn windings and the secondary-side single-turn windings is determined based on the primary-to-secondary turn difference of the PCB transformer. Wherein: When the number of primary-side single-turn branch windings is greater than the number of secondary-side single-turn branch windings, the lateral interleaving method includes: in the horizontal projection of the primary-side single-turn windings and the secondary-side single-turn windings, each secondary-side single-turn branch winding is located in the gap between each primary-side single-turn branch winding; when the number of primary-side single-turn branch windings is less than the number of secondary-side single-turn branch windings, the lateral interleaving method includes: in the horizontal projection of the primary-side single-turn windings and the secondary-side single-turn windings, each primary-side single-turn branch winding is located in the gap between each secondary-side single-turn branch winding. When the primary-secondary turn difference is equal to -1, the longitudinal interleaving method includes: using a fully interleaved structure to longitudinally interleave each of the primary single-turn windings and each of the secondary single-turn windings, wherein the secondary single-turn windings are used as the top and bottom layers of the fully interleaved structure; when the primary-secondary turn difference is less than -1, the longitudinal interleaving method includes: using a segmented interleaved structure to longitudinally interleave each of the primary single-turn windings and each of the secondary single-turn windings, wherein each segment adopts a fully interleaved structure. When the primary-secondary turn difference is equal to 1, the longitudinal interleaving method includes: using a fully interleaved structure to longitudinally interleave each of the primary single-turn windings and each of the secondary single-turn windings, wherein the primary single-turn windings are used as the top and bottom layers of the fully interleaved structure; when the primary-secondary turn difference is greater than 1, the longitudinal interleaving method includes: using a segmented interleaved structure to longitudinally interleave each of the primary single-turn windings and each of the secondary single-turn windings, wherein each segment adopts a fully interleaved structure; Based on the number of primary side single-turn branch windings and the number of secondary side single-turn branch windings, the branch windings of the primary side single-turn windings and the secondary side single-turn windings are designed in parallel. Based on the longitudinal and transverse interleaving methods, the primary side single-turn windings and the secondary side single-turn windings are designed in an interleaving manner, and the PCB winding board is obtained in this way.

2. The design method for a PCB transformer according to claim 1, characterized in that, The method for determining the window size includes: determining the window size based on the power rating of the PCB transformer.

3. The design method for a PCB transformer according to claim 2, characterized in that, The design method further includes: determining the material of the magnetic core based on the switching frequency of the PCB transformer, and then determining the magnetic core by means of the window size and material of the magnetic core.

4. The design method for a PCB transformer according to claim 1, characterized in that, The width of the single-turn winding satisfies the formula Where W is the width of a single-turn winding, W W W is the window width. R The width is for safety regulations; when the PCB transformer is a step-up transformer, the width of the single-turn winding is the width of the primary single-turn winding; when the PCB transformer is a step-down transformer, the width of the single-turn winding is the width of the secondary single-turn winding.

5. The design method for a PCB transformer according to claim 1, characterized in that, The number of single-turn branches satisfies the formula ; When the PCB transformer is a step-up transformer, the number of primary single-turn branch windings satisfies the formula. The number of secondary single-turn branch windings satisfies the formula ; When the PCB transformer is a step-down transformer, the number of single-turn branch windings on the secondary side satisfies the formula. The number of primary side single-turn branch windings satisfies the formula Where n is the number of single-turn branches, W is the width of a single-turn winding, and w i n is the width of the branch winding. p n is the number of single-turn branch windings on the primary side. s This represents the number of single-turn branch windings on the secondary side.

6. The design method for a PCB transformer according to claim 1, characterized in that, The method for longitudinally interleaved layout using a segmented interleaved structure includes: determining the number of segments; dividing each primary-side single-turn winding and each secondary-side single-turn winding into multiple segments based on the number of segments; and using a fully interleaved structure to longitudinally interleave each primary-side single-turn winding and each secondary-side single-turn winding in each segment; wherein, the number of segments satisfies the formula... m is the number of segments, max(N) P N S ) is N P and N S The maximum value in, min(N) P N S ) is N P and N S The minimum value in N P N represents the number of single-turn windings on the primary side. S This represents the number of single-turn windings on the secondary side.

7. The design method for a PCB transformer according to claim 1 or 6, characterized in that, In the fully interleaved structure, when the primary-secondary turn difference is less than 0, in the vertical projection of the primary winding and the secondary winding, each primary single-turn winding is located in the gap between each secondary single-turn winding. When the primary-secondary turn difference is greater than 0, in the vertical projection of the primary winding and the secondary winding, each secondary single-turn winding is located in the gap between each primary single-turn winding.

8. A PCB transformer, characterized in that, The PCB transformer includes: Magnetic core and PCB winding board; The magnetic core includes a first magnetic core body and a second magnetic core body, which are arranged opposite each other through pillars to form a window. The pillars include edge pillars and a center pillar. The PCB winding board is fixed in the window by the central post; The magnetic core is obtained using the design method described in claim 3, and the PCB winding board is obtained using the design method described in any one of claims 1, 2, 4-7.

9. A DC / DC converter, characterized in that, The DC / DC converter includes: the PCB transformer as described in claim 8.

10. A power supply module, characterized in that, The power module includes: the DC / DC converter as described in claim 9.

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